A safety device for vehicle occupants is discussed in DE 195 42 085 B4, a capacitor for the energy storage being provided, and a first voltage converter being provided which is connected to the vehicle battery and which steps up the voltage of the vehicle battery to a multiple of the voltage of the vehicle battery, and which charges the capacitor with this higher voltage. A second voltage converter is provided for connection via its output to an input of a voltage stabilizer. In addition, a microcontroller which controls the voltage converters is provided, and the voltage converters are controllable by a serial interface of the microcontroller. A device and a method for charging an electrical energy storage device are discussed in DE 10 2004 057 690 A1. Active current limitation is provided in a main current path in order to limit a supply current to a given maximum current. A voltage converter device is situated downstream from the current limiting device for raising the potential of the electrical energy storage device above a supply potential.